Design and Development of Ag-Sheathed Bi-Based High-Tc Superconducting Wires with Low AC Losses by Introducing Oxide Resistive Barriers

本研究的目的是通过引入丝间氧化物阻挡层来研制低交流损耗的银套铋系(Bi2223)高温超导线材。为了抑制对Bi2223超导体相形成和性能的不利影响，选择了Ca2CuO(CCO)和SrZrO(SZO)作为阻挡层材料。从输运性质和横向矩阵电阻率的考察中发现，SZO更有效地抑制了临界电流密度(JC)的恶化，并抑制了交流外场下的丝间电磁耦合。最终获得了77K时约20kAcm~(-2)的Jc，77K时270 Hz的自场和耦合频率Fc，以及垂直于带材更宽表面的交流外场。根据这些成果，势垒带在50赫兹附近的垂直场损失比传统的4 mm宽完全耦合细丝带的场损失低70%-80%。

The aim of this study is development of Ag-sheathed Bi-based (Bi2223) high-Tc superconducting wires with low-AC loss by introducing interfilamentary oxide resistive barriers. In order to suppress the side effect on the phase formation and properties of Bi2223 superconductor, Ca2CuO3 (CCO) and SrZrO3 (SZO) were selected as barrier materials. From the examination of transport properties and transverse matrix resistivity, SZO was found to be more effective to suppress the deterioration of critical current density (Jc) and also to suppress the interfilamentary electromagnetic coupling under an AC external field. Finally, Jc around 20 kAcm-2 at 77 K and self-field and coupling frequency fc of 270 Hz at 77 K and AC external field perpendicular to the broader face of tape could be achieved simultaneously. According to these achievements, perpendicular field losses around 50 Hz for barrier tape were 70-80% lower than those for conventional 4 mm-width tape with fully coupled filaments.